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Finding the Fourth Proportional to 1,121.14, 1,680.74 and 390.62

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Solution

The fourth proportional to 1,121.14, 1,680.74 and 390.62 is: 585.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.14 : 1,680.74 = 390.62 : x
  2. Step 2: Convert to fraction form
    1,121.14/1,680.74 = 390.62/x
  3. Step 3: Cross multiply
    1,121.14x = 1,680.74 × 390.62
  4. Step 4: Simplify right side
    1,121.14x = 656,522.26
  5. Step 5: Solve for x
    x = 656,522.26/1,121.14
  6. Step 6: Final answer
    x = 585.59

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.